I have on my 2002 XK8 a recurring restricted performance mode. The codes are always the same & regularly are not the reason for the restriction. The car at some point has a front end impact. Not particularly severe no damage to the chassis just bumpers & valence. But the CPU despite clearing the fault occasionally goes into Restricted mode. Each time this happens back yup the garage diagnostic same fault codes, reset, & fine for months. So rather that keep going back to the garage is like to buy a diagnostic & reset reader. So looking for suggestions for a reasonably priced machines?
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Or post the codes & perhaps you'll get help to fix their cause...

 

He's got another post titled the same JagV8, that's where the other responses are.